Influence of Fuel Aromatics Type on the Particulate Matter and NO _x Emissions of a Heavy-Duty Diesel Engine

The influence of fuel aromatics type on the particulate matter (PM) and NO_x exhaust emissions of a heavy-duty, single-cylinder, DI diesel engine was investigated. Eight fuels were blended from conventional and oil sands crude oil sources to form five fuel pairs with similar densities but with different poly-aromatic (1.6 to 14.6%) or total aromatic (14.3 to 39.0%) levels. The engine was tuned to meet the U.S. EPA 1994 emission standards. An eight-mode, steady-state simulation of the U.S. EPA heavy-duty transient test procedure was followed.

The experimental results show that there were no statistically significant differences in the PM and NO_x emissions of the five fuel pairs after removing the fuel sulphur content effect on PM emissions. However, there was a definite trend towards higher NO_x emissions as the fuel density, poly-aromatic and total aromatic levels of the test fuels increased.